1. Field of the Invention
The present application relates generally to a handle for tools and, more particularly, to an improved composite handle for hardware or gardening tools.
2. Description of the Related Art
Handles for gardening and hardware tools, such as shovels, rakes, hoes, spades and forks, come in a wide variety of sizes and shapes and are manufactured from a number of materials. A vast majority of these handles are traditionally constructed entirely from wood, and while they exhibit satisfactory chemical, physical and mechanical properties in most circumstances, in other circumstances they have insufficient strength capability and do not last as long as desired when exposed to the environment.
Several approaches have been proposed for overcoming this shortcoming, including the substitution of reinforced plastic for wood. While plastic handles have been developed which in some respects out perform wood, an entirely practical plastic handle has yet to be developed. For instance, since the material selected must approximate the chemical, physical and mechanical properties of wood, only a limited number of plastics are usable for leverage-type tools such as shovels. Moreover, when plastic handles are produced, such as described in U.S. Pat. Nos. 4,418,732 and 4,639,029, they generally comprise several components which necessitate a lengthier and costlier manufacturing process. In the highly competitive garden and hand tool industry, such added costs provide a significant marketing disadvantage.
Further attempts to overcome these disadvantages have involved the use of composite materials. Composite handles generally consist of an inner core of one material surrounded by an outer shell of a different, usually plastic, material. Some known handles, for example, have a fiberglass core surrounded with a coating of injected molded thermoplastic resins, such as polyethylene or polypropylene. Handles such as these are most suited for impact-type tools, such as axes and sledgehammers, where the outer shell can absorb shock and where significant bending leverage is not applied to the tool.
Another type of composite handle is manufactured by HISCO, of Oklahoma City, Okla. This handle includes a cross-sectionally uniform wood core which is encased in a polymeric tube reinforced by glass fiber rovings. Such a tube is applied to the wood core by a pultrusion process which requires the core and finished handle to have a non-varying cross-sectional dimension. Consequently, neither the core nor the finished handle can be contoured or shaped.
It is very desirable for a tool handle to have a variable cross-section. The bending moment applied to a leverage-type tool such as a shovel is not constant throughout the entire length of the handle. Generally, it is greatest near the tool socket and lowest near the hand grip. A cross-sectional shape which has its greatest cross-sectional size near the socket and a lesser cross-sectional size near the hand grip is capable of providing a uniformly stressed member when subjected to leverage use. Thus, an uncontoured handle such as produced by HISCO requires substantially more material and larger cross-section than necessary near the hand grip portion in order for the portion near the tool to be of sufficient size to withstand the bending stress. Furthermore, it is desirable to contour the extreme end portion of the handle proximate the user to have a slightly increasing diameter so that a natural grip is formed in the handle. A constant diameter handle provides a core which is too thick to facilitate comfortable and convenient usage, and does not provide such a convenient grip.
For all these reasons, it is apparent that the prior art has not been able to supply a handle which meets the requirements for strength, weather-resistance, and contoured outer dimensions.